As a water discharge system that detects a human body to control the start of water discharge automatically, there is a water discharge system that uses a human body or a human hand as an object to be detected, detects the presence or absence of the object to be detected based on the intensity of the reflected radio wave from the object to be detected, and performs the stop of water discharge if the object to be detected is not detected.
When a transmission wave such as a microwave comes into contact with an object to be detected, a reflected wave or a transmitted wave is generated. The object to be detected such as a human body can be detected by receiving the reflected wave or the transmitted wave, and the water discharge system can be used for a faucet apparatus and the like.
JP-A 9-80150 (1997)(Kokai) discloses a human body detection system that receives the reflected wave of a radiated microwave from an human body, finds the power spectrum of the Doppler frequency signal of the reflected wave, and compares the peak value of the power spectrum and a prescribed threshold to detect the human body.
Patent Citation 1: JP-A 9-80150 (1997)